This invention relates to a development process for an electrophotographic duplicator employing magnetic toner.
More particularly, this invention relates to a development process for an electrophotographic duplicator employing magnetic toner and a selenium, organic semiconductor, or cadmium sulfide type photosensitive material.
Development processes for electrophotographic duplicators employing magnetic toners are known in the art. For example, a conventional process for an electrophotographic duplicator employing magnetic toner has been used in developing an electrostatic latent image formed on the surface of a zinc oxide type photosensitive material. In this particular process, a paper applied with photoconductive zinc oxide and with an insulating resin binder, commonly referred to as the master paper, is normally employed. The use of the zinc oxide photosensitive material makes it practical to use magnetic toner in the development process because the photosensitive material has a fine roughness, thereby allowing for a concentrated electrical conductivity pattern thereon. The magnetic toner, therefore, has a high adhesion power to the photosensitive material.
A major drawback, however, with respect to the use of zinc oxide photosensitive material in a development process is that the master paper is not durable and when magnetic toner is employed a high magnetic power of more than 1,000 gauss for conveying the magnetic toner to the photosensitive material is required.
To date, the known development processes employing a photosensitive material of a selenium, organic semiconductor or cadmium sulfide type either have not been practical, are uneconomical, or do not provide a high quality duplication. One principal difficulty occurs in applying magnetic toner in this process because of a relatively smooth surface of the photosensitive material and uniform distribution of the electrical conductivity field thereon. Therefore, adhesion of the magnetic toner is not as effective as with a zinc oxide photosensitive material.
In summary, there has been no development process for an electrophotographic duplicator employing magnetic toner with a selenium, organic semiconductor, or cadmium sulfide type photosensitive material that teaches a combination of parameters for economic, practical, and high quality duplication.